**Fuel Pressure Problem**

[jaydaniels]

Well, this is a strange one. Buddy of mine has an 06 Apex. Went to start at the first of the seaon and sled started up. Then all of a sudden started working funny and we see fuel everywhere! Fuel line popped off. I figured that the clamp wasn't one so put the clamp on and it then seemed fine but idled funny and seemed to be running rich. Adjusted the CO setting down to -20 and sled worked much better. After one weekend of riding the sled seemed to work fine but it was much harder on gas then my own Apex. This weekend we go the take off and he's sled quits. Once again, the fuel line pops off. Thought maybe the clamps were bad and or wrong fuel line so we went and got screw clamps. This kept the line from popping off but the sled was generating so much fuel pressure that it actually blew a hole through the side of the gas line. Anyone have any ideas whats going on. Fuel pressure regulator maybe?? I've done a ton of searching and haven't seen or heard of anyone having this problem before. Pretty sure it's the correct fuel line as its shaped for the sled.

 

[jamesc]

don't have much experience with these sleds yet but as you mentioned first thing i would suspect is the regulator sticking closed. can you get a fuel pressure gauge in the system to see how much pressure it's making?

 

[jaydaniels]

Not sure where to get a pressure gauge. What do they look like??

 

[FLYBYU]

http://www.ty4stroke.com/viewtopic.php? ... ht=#838270

 

[jaydaniels]

Thanks. I'll have to pick one up. Where exactly is the fuel pressure regulator? Is it adjustable or could it stick?

 

[FLYBYU]

Thanks. I'll have to pick one up. Where exactly is the fuel pressure regulator? Is it adjustable or could it stick?

It's in the fuel rail on the opposite side of the fuel line. It's not adjustable.

 

[jaydaniels]

So how exactly does one work and what effect does fuel pressure have on how the motor operates.

 

[jaydaniels]

Anyone?? Just curious how the fuel pressure regulator works. Is there a sensor that monitors the pressure and turns on the pump when needed?

 

[jamesc]

the fuel pump runs continously and supplies more fuel than the engine needs. the regulator is meant to maintain a preset amount of pressure on the fuel rail whatever the engine doesn't use is returned to the tank. as engine load goes up fuel demand goes up. the regulator closes off reducing the amount of fuel returning to the tank to maintain the preset pressure. this is critical as it has a direct impact on the fuel mixture. as the engine is loaded and/or speed increases the injectors will cycle faster and stay open longer supplying more fuel to the engine. if the rail pressure isn't at it's preset proper spec the engine will either run lean if the pressure is too low or rich if it is too high. you said the sled is running rich and pushing hoses apart which would most likely indicate the regulator is sticking closed causing the fuel pressure to be too high.

it woudn't be pratical to explain how a regulator works in a post maybe someone can link to something to better explain.

 

[FLYBYU]

the fuel pump runs continously and supplies more fuel than the engine needs. the regulator is meant to maintain a preset amount of pressure on the fuel rail whatever the engine doesn't use is returned to the tank. as engine load goes up fuel demand goes up. the regulator closes off reducing the amount of fuel returning to the tank to maintain the preset pressure. this is critical as it has a direct impact on the fuel mixture. as the engine is loaded and/or speed increases the injectors will cycle faster and stay open longer supplying more fuel to the engine. if the rail pressure isn't at it's preset proper spec the engine will either run lean if the pressure is too low or rich if it is too high. you said the sled is running rich and pushing hoses apart which would most likely indicate the regulator is sticking closed causing the fuel pressure to be too high.

it woudn't be pratical to explain how a regulator works in a post maybe

someone can link to something to better explain.

That's it.

 

[jaydaniels]

So, would I be correct in assuming that the pressure in the fuel line going from the tank to the regulator would be the highest when the pump is on but sled is not running. The fuel line blowing off is the one from the tank to the regulator so its seems like it may not be a regulator problem but that the pump is creating too much pressure.

 

[jamesc]

So, would I be correct in assuming that the pressure in the fuel line going from the tank to the regulator would be the highest when the pump is on but sled is not running. The fuel line blowing off is the one from the tank to the regulator so its seems like it may not be a regulator problem but that the pump is creating too much pressure.

no and no. the only reason the fuel pressure would be higher with the pump on and engine off is if the regulator is not working properly.

the pump pumps fuel from the tank to the fuel rail where it feeds the injectors. the job of the regulator is to keep a CONSTANT specified pressure on this rail by varying the amount of fuel it lets return to the tank, this is a loop. the pump is not creating too much pressure. it is a positive displacement pump and is designed to pump a specific amount of fuel. if there is too much fuel pressure in the system it is because the regulator is sticking closed not allowing enough to return to the tank. if the regulator were to stick open it would allow too much to return to the tank causing the rail pressure to be too low and the engine would run lean or possibily not at all

again the pressure in this system is supposed to be constant, the component that does this is the regulator. it does this by controlling how much it allows to be returned to the tank. i should also note that the pressure regulator may well be referenced to the engine vacuum so you should check the vacuum hoses going from it to the throttle body assembly. i think the stock pressure is around 36 PSI

 

[jaydaniels]

Okay, thanks for the explaination. I think I was looking at things backwards. The fuel line that keeps pushing off might actually be the return line. It is the line on the brake side that comes out close to the regulator. Can anyone verify this? If this line is coming off it makes me think that maybe there is restriction in the return line to the tank. Its actually blowing holes right through the line.

 

[FLYBYU]

That doesn't make any sense because the return into tank has nothing that would restrict it.

 

[jaydaniels]

That doesn't make any sense because the return into tank has nothing that would restrict it.

So is the gas line on the brake side of the fuel rail the return line??